1. Field of the Invention
This invention relates to remotely adjustable screens and particularly concerns screens having louvers attached to permanent magnet rotors that are controlled by direct electromagnetic fields.
2. Description of the Prior Art
U.S. Pat. No. 3,524,281 dated Aug. 18, 1970 discloses a screen having ribbon-like louvers supported only at their ends, each end being attached to a separate permanent magnet rotor. The louver attitude is determined, except at open and closed louver limits, by equilibrium between a control torque produced by a transverse electromagnetic field and a restoring torque that tends to maintain each rotor at a predetermined angle of repose. The transverse control field is created by elongated coils, one or a pair on opposite edges of the screen, extending the length of the beams that contain the permanent magnet rotors.
Unfortunately the potential of the prior invention is obscured by the complexity of the illustrated embodiment and its obvious unsuitability for manufacture. Radical simplification of the original design has subsequently been made. For example, sturdy, inexpensive anticlastic suspensions of the rotors are described in U.S. Pat. No. 4,797,591 dated Jan. 10, 1989.